Trapezius Muscle

The trapezius muscle (Trapz) is a large muscle consisting of four parts covering the upper back, shoulders and neck. It is used in shrugging the shoulders and with overhead movements.

Trapezius muscle explained

Part 1: Upper fibres of the cervical vertebrae. This is the weakest part of the muscle and only provides minor elevation of the clavicle.

Part 2: The area commonly known as upper trapz. This is a strong elevator, rotator and retractor of the scapula.

Part 3: The mid-portion of the Trapzius. These fibres are mainly responsible for scapula retraction.

Part 4: The lower fibres of Trapezius. This part of the muscle assists in retraction and rotation.

When all parts of the muscle work together they have the effect of simultaneously elevating and retracting the scapula. The Trapezius is used most commonly to fix the scapula to allow the Deltoid to move the Humerus.